That means new roof, HVAC, water heater, landscaping, painting, upkeep and so on.

Appears the guests may have left the faucet "on" when the pipes were frozen and when no water came out, forgot to turn it "off".What may have caused the overflow of the sink is maybe the drain lines were also frozen?

When it was clear water was running from the unit.

If they can't do that, keep shopping.This may require digging up the foundation, sealing it from the outside, and installing a french drain to keep water away from the walls.

I've also had guests buy their own TP and trash bags and leave the extra.As for toiletries, I leave the traditional "Starter Set" of shampoo, a little bar soap, conditioner, and lotion  (the tiny hotel bottles). 

8 - What type of natural drainage will there be on the site/9 - What type of water supply will you be using?

Water overflowing the sink, seems more plausible than some missing caulk.  

The first farmer tries to plant, water, and harvest everything himself.

It costs the same thing to fix a hot water heater or remodel a bathroom on a $200K house as a $100K house.   

Start with maintenance notes that you may regularly reference, such as air filter size, water shut-off location, etc.